1. Technical Field
The present invention relates to a function layer ink used for forming a function layer, a method for manufacturing a light-emitting element, and a light-emitting device and an electronic apparatus.
2. Related Art
An organic electroluminescent element (light-emitting element) has a structure including at least one light-emitting organic layer (luminescent layer) between an anode and a cathode. In light-emitting elements of this type, electrons and holes are injected to the luminescent layer respectively from the cathode and the anode by applying an electric field between the cathode and the anode, and the electrons and the holes form excitons in the luminescent layer. When the excitons disappear (when electrons and holes are recombined with each other), part of the energy is emitted as fluorescence or phosphorescence.
In general, a light-emitting element has a hole injection layer on the anode, and a hole transport layer or a luminescent layer is disposed on the hole injection layer.
These layers may be formed by applying an ink in which the material of the layer to be formed is dissolved or dispersed, as described in, for example, JP-A-2008-77958.
In these years, low-molecular-weight luminescent materials, as well as macromolecular luminescent materials, are used as luminescent materials in coating processes such as liquid election methods, as disclosed in, for example, JP-A-2006-190759 and JP-A-2011-108462.
In JP-A-2006-190759 and JP-A-2011-108462, however, low-molecular-weight luminescent materials are liable to aggregate due to the intermolecular interaction of the material in the process of forming the luminescent layer. This makes it difficult to form a luminescent layer having a uniform thickness. In addition, the aggregation of the material may result in failure in forming the luminescent layer and cause emission failure. In other words, it is difficult to form a luminescent layer having desired optical properties with a high yield.